Patient support apparatus having an air cell grid and associated method

ABSTRACT

An apparatus ( 10 ) for supporting a patient during a medical procedure includes a bead bag ( 18 ) that is filled with compressible beads ( 20 ) and that forms a lower layer of the apparatus ( 10 ). The apparatus ( 10 ) also includes a layer of foam material ( 30 ) that is located above the bead bag and an air cell grid ( 36 ) that has a plurality of inflatable air cells ( 38 ). The air cell grid ( 36 ) forms an upper layer of the apparatus ( 10 ) and provides a soft surface upon which the patient lies. The bead bag ( 18 ), when subjected to a vacuum, becomes rigid for supporting the air cell grid ( 36 ) against the patient for helping to maximize a surface area of contact between the patient and the apparatus ( 10 ).

TECHNICAL FIELD

The present invention relates to an apparatus for supporting a patientduring a medical procedure and to a method of using the apparatus tosupport a patient. More particularly, the present invention relates to asurgical support surface for supporting a patient during a surgicalprocedure and to a method of use for the surgical support surface.

BACKGROUND OF THE INVENTION

A surgical support surface supports a patient on a surgical table. Atypical surgical support surface includes a foam rubber interior and aplastic cover. When a patient lies on the typical surgical supportsurface, the pressure interface between the patient and the surgicalsupport surface is concentrated at particular locations on the patient'sbody, such as at the patient's heals, sacrum, scapulas, and cranium.Pressure ulcers may occur at locations of high interface pressurebetween the patient and the surgical support surface. Additionally, whenthe surgical table is moved or tilted, areas of high interface pressureare subject to shear. It is desirable to minimize areas of highinterface pressure between the patient and the surgical support surfaceand to prevent the occurrence of shear during movement of the surgicaltable.

U.S. Pat. No. 5,966,763 attempts to address the problem of highinterface pressure between the patient and a surface pad. A vacuum beadbag is placed in the surface pad at a location for engaging the patient.The vacuum bead bag conforms to the contour of the patient to increasethe surface area of contact between the patient and the surface pad.Once the vacuum bead bag conforms to the contour of the patient, thevacuum bead bag is rigidified for supporting the patient during themedical procedure.

In addition to minimizing areas of high interface pressure between thepatient and the surgical support surface and preventing the occurrenceof shear, it is also desirable for a surgical support surface to beradiolucent. Radiolucency of the surgical support surface enables x-raysof a patient to be taken while the patient is located on the surgicalsupport surface.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for supporting a patientduring a medical procedure. The apparatus comprises a bead bag that isfilled with compressible beads. The bead bag forms a lower layer of theapparatus. The apparatus also comprises a layer of foam material that islocated above the bead bag and an air cell grid that has a plurality ofinflatable air cells. The air cell grid forms an upper layer of theapparatus and provides a soft surface upon which the patient lies. Thebead bag, when subjected to a vacuum, becomes rigid for supporting theair cell grid against the patient for helping to maximize a surface areaof contact between the patient and the apparatus.

According to another aspect, the present invention relates to anapparatus for supporting a patient during a medical procedure. Theapparatus comprises an air cell grid having a plurality of inflatableair cells. Each air cell includes a base wall and an upper wall. Theupper wall moves away from the base wall when the air cell is inflatedinto an expanded condition. The apparatus also comprises an electricalswitch for indicating a collapsed condition of an associated air cell ofthe air cell grid. The electrical switch includes a first electricalcontact that is located on the base wall of the associated air cell anda second electrical contact that is located on the upper wall of theassociated air cell. The first and second electrical contacts come intoengagement with one another in response to the associated air cellmoving into the collapsed condition.

According to yet another aspect, the present invention relates to amethod of supporting a patient on a support structure having an air cellgrid that includes a plurality of inflatable air cells. In accordancewith the inventive method, the air cells of the air cell grid areinflated into an expanded condition. The air cells of the air cell gridare vented to atmosphere while maintaining the air cells in the expandedcondition. Air cells of the air cell grid are isolated from one anotherand from atmosphere. The patient is positioned on the support structureabove the air cell grid. The air cells are then placed in fluidcommunication with one another to equalize air pressure throughout theair cell grid for helping to equalize an interface pressure between thepatient and the support structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will becomeapparent to those skilled in the art to which the present inventionrelates upon reading the following description with reference to theaccompanying drawings, in which:

FIG. 1 is a perspective cutaway view of an apparatus constructed inaccordance with the present invention;

FIG. 2 is a perspective cutaway view of a group of air cells of an aircell grid of the apparatus of FIG. 1;

FIG. 3 is a top view of the group of air cells of FIG. 2;

FIG. 4 is a view taken along line 4-4 in FIG. 3;

FIG. 5 is a flow diagram illustrating a method in accordance with thepresent invention;

FIG. 6 is an exploded perspective view of a group of air cellsconstructed in accordance with an alternative embodiment of the presentinvention;

FIG. 7 is an exploded perspective view of a group of air cellsconstructed in accordance with a second alternative embodiment of thepresent invention; and

FIG. 8 is a sectional elevation view of a portion of an apparatusconstructed in accordance with a second embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a perspective cutaway view of an apparatus 10 constructed inaccordance with the present invention. The apparatus 10 is a surgicalsupport surface for supporting a patient (not shown) during a surgicalprocedure. Alternatively, the apparatus 10 may be used for supporting apatient during a medical procedure other than surgery. For example, theapparatus 10 may be used in an emergency vehicle, such as an ambulance,in which medical procedures are performed on a patient whiletransporting the patient to a medical facility.

The apparatus 10 illustrated in FIG. 1 is to be positioned on a surgicaltable (not shown) below a patient. The apparatus 10 includes a pliableelastic cover 12 that defines an upper surface 14 and a lower surface(not shown) of the apparatus 10. The lower surface of the apparatus 10lies on the surgical table and the upper surface 14 of the apparatussupports the patient. The apparatus 10 functions to maximize the surfacearea of contact between the patient and the upper surface 14 so as tominimize areas of high interface pressure between the patient and theapparatus. Additionally, the apparatus 10 provides stability forretaining the patient in position during movement of the surgical tableso as to minimize the occurrence of shear on the patient.

As shown in FIG. 1, the apparatus 10 includes a bead bag 18. The beadbag 18 is a pliable plastic bag in which is stored a plurality ofcompressible beads 20. A valve 24, shown schematically in FIG. 1,extends through the bead bag 18 for allowing airflow into and out of thebead bag. FIG. 1 illustrated the valve 24 extending outwardly throughthe cover 12 of the apparatus 10. When subjected to a vacuum, the beadbag 18 stiffens, i.e., becomes more rigid. Under a partial vacuum, thebead bag 18 becomes moldable and has a stiffness sufficient to remain inits molded condition. The bead bag 18 becomes rigid when the vacuum isincreased. When rigid, the bead bag 18 is no longer moldable.

The bead bag 18 forms a lower layer of the apparatus 10. Only theportion of the cover 12 that defines the lower surface of the apparatus10 extends between the bead bag 18 and the surgical table. The bead bag18 has a length and a width that are substantially equal to a length andwidth of the apparatus 10. In one embodiment, the bead bag 18 has awidth of approximately three feet and a length of approximately sevenfeet. A depth of the bead bag 18, measured vertically between a lowersurface (not shown) of the bead bag and an upper surface 26 of the beadbag when the bead bag is at atmospheric pressure, i.e., in a non-moldedcondition, is approximately one and a half to two inches. It should beunderstood that the dimensions of the bead bag 18 might be varieddepending upon the intended use of the apparatus 10. Also, thedimensions of the bead bag 18 may vary as a result of molding of thebead bag during use.

A layer of highly resilient foam material 30 overlies the upper surface26 of the bead bag 18. The layer of foam material 30 preferably isformed from polyurethane. The layer of foam material 30 has a length anda width that are substantially equal to the length and width of the beadbag 18 and, in one embodiment of the invention, has a depth that isapproximately three-quarters of an inch.

An air cell grid 36 overlies the layer of foam material 30. The air cellgrid 36 includes a plurality of air cells 38. All of the air cells 38 ofthe air cell grid 36 may be interconnected with one another with aseparate valve (not shown) associated with each air cell. In anexemplary embodiment of the apparatus 10, the air cells 38 are formed ingroups with the groups of air cells being interconnected, as isdescribed below.

FIG. 2 is a perspective cutaway view illustrating an exemplary group 44of air cells 38. The group 44 illustrated in FIG. 2 includes four aircells 38. The air cells 38 in the group 44 are formed in a two-by-twoarray. The group 44 of air cells 38 preferably is molded from vinyl. Thevinyl enables each air cell 38 of the group 44 to be inflated into anexpanded condition but prevents ballooning of the air cells. As shown inFIG. 3, the group 44 also includes four molded air channels 46. Themolded air channels 46 are disposed between laterally adjacent air cells38 and longitudinally adjacent air cells of the group 44.

A valve 48 (FIG. 4) is associated with the group 44 of air cells 38. Thevalve 48 has open and closed conditions. In the open condition, air mayflow through the valve 48 and into or out of the air cells 38 of thegroup 44. In the closed condition, air is prevented from entering orexiting the group 44 of air cells 38. Thus, the valve 48, when in theopen condition, may be used for interconnecting the group 44 of aircells 38 with other groups of air cells in the air cell grid 36 and,when in the closed condition, may be used for isolating the group 44 ofair cells 38 from other groups of air cells in the air cell grid 36.

With reference again to FIG. 1, groups of air cells 38 are arrangedlaterally and longitudinally adjacent to one another to completely coverthe length and width of the layer of foam material 30. The valves of thegroups of air cells 38, such as valve 48 of group 44, are interconnectedwith one another. Preferably, conduits (not shown) located within theapparatus 10 and under the air cell grid 36 interconnect the valves. Anair valve 52 (FIG. 1) also connects to the conduits for enabling airflowinto and out of the air cell grid 36. FIG. 1 illustrates the air valve52 extending outwardly from the cover 12. Alternatively, each group ofair cells 38 of the air cell grid 36 may include a conduit that extendsoutside of the cover 12 of the apparatus 10 and valves forinterconnecting the groups of air cells may be located outside of thecover 12.

As shown in FIG. 4, each air cell 38 of the air cell grid 36 includes abase wall 56 and an upper wall 58. A common sheet of material may formthe base walls 56 of all of the air cell 38 of the group 44. The upperwall 58 of each air cell 38 is affixed to the base wall 56. Preferably,the upper wall 58 of each air cell 38 is molded to its associated basewall 56.

The base wall 56 of each air cell 38 is substantially planar and has agenerally square configuration. An air channel 60 extends through a basewall 56 of one of the air cells 38 in the group 44. The air channel 60is in fluid communication with the valve 48 and enables airflow into andout of the air cells 38 of the group 44.

The air cells 38 each have a fully expanded condition. The air cells 38are illustrated in FIGS. 2-4 in the fully expanded condition. When inthe fully expanded condition, each air cell 38 has a height ofapproximately two and a half inches.

When an air cell 38 is in the fully expanded condition, the upper wall58 includes a generally square base portion 64 and a domed upper portion66. The base portion 64 (FIG. 2) includes four sidewalls 68. FIG. 4 onlyillustrates two of the sidewalls 68 of each air cell 38. Each sidewall68 extends upwardly from the base wall 56 at an acute angle relative tothe base wall 56. FIG. 4 illustrates the angle between the sidewall 68and the base wall 56 as angle α. Preferably, angle α is approximately 85degrees. However, it will be understood by those skilled in the art thatthe angle α may be different based on the material used and itsthickness. The sidewalls 68 extend upwardly from the base wall 56 forapproximately one-half of the height of the air cell 38. The domed upperportion 66 of the air cell 38 connects the four sidewalls 68. When theair cell 38 is in the fully expanded condition, the domed upper portion66 of the air cell 38 is located at its farthest distance away from thebase wall 56.

The relative angle between the base wall 56 and the sidewall 68 helpswith the radiolucency of the apparatus 10. When the air cell grid 36 ofthe apparatus 10 is loaded with the weight of the patient, it isunlikely that a large portion of any of the sidewalls 68 of the aircells 38 will extend in a direction perpendicular to an upper surface ofthe surgical table. An x-ray is usually taken at an angle perpendicularto the upper surface of the surgical table. Since it is unlikely that alarge portion of any of the sidewalls 68 of the air cells 38 will extendin the direction of the x-ray, resistance to the x-ray passing throughthe air cell grid 36 is minimized. As a result, the apparatus 10provides sufficient radiolucency for allowing x-rays of a patientpositioned on the apparatus.

The cover 12 of the apparatus 10 completely surrounds the bead bag 18,the layer of foam material 30, and the air cell grid 36. The cover 12 ispreferably made from a material that is easily cleaned and that isnon-absorptive.

As shown schematically in FIG. 1, the apparatus 10 also includes acontrol unit 74. The control unit 74 may be battery operated or mayinclude an electrical cord for receiving electrical power.Alternatively, the control unit 74 and its associated compresses may bemanually operated to either compress air or to pull a vacuum. Thecontrol unit 74 includes an air outlet port 76 and a vacuum inlet port78. Conduit 77 connects the air outlet port 76 of the control unit 74 tothe valve 52. Conduit.79 connects the vacuum inlet port 76 of thecontrol unit 74 to the valve 24. The control unit 74 also includes anair inlet port 82 for connection to a compressed air source (not shown)and a vacuum outlet port 84 for connection to a vacuum source (notshown). Alternatively, the control unit 74 may include a pump (notshown). The air outlet port 76 and the vacuum inlet port 78 may beconnected to the pump for providing compressed air and vacuum,respectively.

The control unit 74 also includes a control knob 86 that is rotated forperforming particular steps associated with the use of the apparatus 10.By way of example, FIG. 5 illustrates a process 500 for using theapparatus 10 for supporting a patient during a medical procedure.Various steps of the process 500 may be associated with rotationalpositions of the control knob 86.

The process 500 of FIG. 5 begins at step 502 at which the control unit74 is powered on. At step 504, the air cells 38 of the air cell grid 36are inflated into a fully expanded condition. To inflate the air cells38 to the fully inflated condition, the control unit 74 controls thesupply of compressed air into the air cell grid 36. The valve associatedwith each group of air cells 38, such as valve 48 of group 44, is openedto allow the air pressure within each air cell to increase. Theincreased air pressure within the air cells 38 expands the air cellsinto the fully expanded condition. From step 504 the process 500proceeds to step 506.

At step 506, the air cells 38 of the air cell grid 36 are vented toatmosphere. To vent the air cells 38 to atmosphere, the valve associatedwith each group of air cells 38 remains in the open condition and thevalve 52 is connected to atmosphere. When the air cells 38 are vented toatmosphere, the air pressure within each air cell substantiallyequalizes with the atmospheric air pressure. Since, at this time, noforces other than atmospheric pressure are being applied to the aircells 38, the air cells remain in the fully expanded condition.

At step 508, the valve associated with each group of air cells 38 isclosed so that the. groups of air cells are isolated from one another.When isolated from one another, the air cells 38 within each group, suchas the air cells of group 44, remain in fluid communication with oneanother through the air channels 46. From step 508 the process 500proceeds to step 510 at which the patient is positioned on the apparatus10. The patient may be positioned in any position on the apparatus 10.Generally, for surgical procedures, the patient is either in a supineposition or in a side-lying position.

At step 512, a partial vacuum is pulled on the bead bag 18. Whensubjected to the partial vacuum, the bead bag 18 becomes moldable andremains in its molded position. At step 514, the medical personnel moldthe bead bag 18 to provide support to areas of the patient that arecommonly subject to low interface pressure, such as the lumbar region ofthe spine when the patient is in the supine position, the perineum, andthe lateral aspects of the thorax and the thighs. After the bead bag 18is molded at step 514, the bead bag 18 is rigidified at step 516. Torigidify the bead bag 18, the vacuum on the bead bag 18 is increased.The process 500 proceeds from step 516 to step 518.

At step 518, the groups of air cells 38 are interconnected, i.e., placedin fluid communication with one another, so that the air pressurethroughout the air cell grid 36 equalizes. To interconnect the groups ofair cells 38, the valve associated with each group of air cells 38 isplaced in the open condition and the valve 52 remains in the closedcondition. When the valve of each group of air cells 38 is opened, theair pressure throughout the air cell grid 36 will equalize. Ideally,when the groups of air cells 38 are interconnected to equalize the airpressure throughout the air cell grid 36, the distance between thepatient and the molded and rigidified bead bag 18 will be relativelyconstant over the entire area of contact between the patient and theapparatus 10.

When the air pressure throughout the air cell grid 36 is equalized, thesurface area of contact between the upper surface 14 of the apparatus 10and the.patient is maximized. As a result, areas of high interfacepressure between the patient and the apparatus 10 are minimized.

At step 520, the medical procedure is performed. The medical proceduremay involve moving or tilting of the surgical table. The apparatus 10 ofthe present invention minimizes movement of the patient during themovement of the surgical table. Also, the use of the layer of foammaterial 30 between the generally soft air cell grid 38 and therigidified bead bag 18 helps reduce shear on the patient. The layer offoam material 30 also provides a baseline level of support for thepatient should a failure occur to the air cell grid 36.

After the medical procedure is performed, the patient is removed fromthe apparatus 10 at step 522. At step 524, the valves 24 and 52 of theapparatus 10 are opened and the bead bag 18 and the air cell grid 36 arevented to atmosphere. When the bead bag 18 is vented to atmosphere, thebead bag 18 becomes soft and returns to its original non-moldedcondition. After the bead bag 18 and the air cell grid 36 are vented toatmosphere, the process 500 ends at step 526.

To prevent areas of high interface pressure between the patient and theapparatus 10, it is desirable to ensure that each air cell 38 of the aircell grid 36 remains at least partially expanded while the patient isbeing supported on the apparatus 10. When an air cell 38 “bottoms out,”i.e., collapses so that the upper wall 58 and the base wall 56 of theair cell 38 come into contact with one another, an area of highinterface pressure between the patient and the apparatus 10 may occur.To help prevent the bottoming out of air cells 38, some or all of theair cells 38 of the air cell grid 36 may be constructed to include anintegral electrical switch for indicating a bottoming out or collapsedcondition of the air cells.

FIG. 6 is an exploded perspective view of a group 44′ of air cells 38′constructed in accordance with an alternative embodiment of the presentinvention. The group 44′ of air cells 38′ of FIG. 6 may be used in theapparatus 10 illustrated in FIG. 1.

The base walls 56′ of the air cells 38′ of the group 44′ are formed froma single sheet 90 of material. A first electrically conductive grid 92is located on an upper surface 96 of the sheet 90. The firstelectrically conductive grid 92 that is illustrated in FIG. 6 includesfour electrical contact 94. One electrical contact 94 is associated withthe base wall 56′ of each air cell 38′ of the group 44′. The firstelectrically conductive grid preferably is screen-printed on the sheet90.

A second electrically conductive grid (not shown) is also associatedwith the upper walls 58′ of the air cells 38′ of the group 44′. Thesecond electrically conductive grid preferably is screen-printed on thesheet upper walls 58′. FIG. 6 illustrates an electrical contact 100 ofthe second electrically conductive grid located on an interior surfaceof each upper wall 58′ of the group 44′. The electrical contact 100 onthe upper wall 58′ of each air cell 38′ extends generallyperpendicularly to the electrical contact 94 on the base walls 56′ ofthe air cell so that a bottoming out of any portion of the air cell willcause the electrical contacts 94 and 100 to engage one another.

The electrical contacts 94 and 100 are electrically coupled to thecontrol unit 74 (FIG. 1). When the electrical contacts 94 and 100 cometogether, i.e., engage one another, an electrical signals is sent to thecontrol unit 74 indicating that an air cell 38′ has bottomed out. Thecontrol unit 74 may include an alarm for indicating to the medicalpersonnel performing the medical procedure that an air cell 38′ hasbottomed out. Additionally, or alternatively, the control unit 74 mayinclude an automatic inflation mode that is responsive to the electricalsignal indicative of a bottomed out condition for controlling the supplyof compressed air and the valve 52 of the apparatus 10 for providing airinto the air cell grid 36 to inflate the air cells 38′. When theelectrical contacts 94 and 100 disengage as a result of inflation of thebottomed out air cell 38′, the control unit 74 discontinues inflation ofthe air cell grid 36 and closes the valve 52 associated with the aircell grid.

FIG. 7 is an exploded perspective view of a group 44″ of air cells 38″constructed in accordance with a second alternative embodiment of thepresent invention. The group 44″ of air cells 38″ of FIG. 7 may be usedin the apparatus 10 illustrated in FIG. 1.

The base walls 56″ of the air cells 38″ of the group 44″ are formed fromtwo sheets of material. A lowermost layer 104 is formed from anelectrically conductive material. In one embodiment of the invention,the lowermost layer 104 is formed from an electrically conductive vinyl.An insulating layer 106 overlies the lowermost layer 104. The insulatinglayer 106 is electrically non-conductive. A plurality of cutouts 108extends through the insulating layer 106. A cutout 108 is associatedwith the base wall 56″ of each air cell 38″ of the air cell grid 36.Each cutout 108 in the insulating layer 106 is square and extends over alarge portion of the base wall 56″ of the associated air cell 38″. Theportion 110 of the lowermost layer 104 that is open through anassociated cutout 108 at the base wall 56″ of each cell forms anelectrical contact 112.

The upper wall 58″ of each air cell 38″ is formed from an electricallyconductive material. In one embodiment of the invention, the upper wall58″ is formed from an electrically conductive vinyl. The upper wall 58″also forms an electrical contact 114.

The electrical contacts 112 and 114 are electrically coupled to thecontrol unit 74 (FIG. 1). When the electrical contacts 112 and 114 cometogether, an electrical signals is sent to the control unit 74indicating that an air cell 38″ has bottomed out.

FIG. 8 is a sectional elevation view of a portion of an apparatus 10′constructed in accordance with a second embodiment of the presentinvention. Structures of the apparatus 10′ of FIG. 8 that are the sameas or similar to those described with reference to the apparatus 10 ofFIG. 1 are indicated in FIG. 8 with the same reference numbers as usedwith regard to FIG. 1.

The cover 12 of the apparatus 10′ of FIG. 8 is formed from a gasimpenetrable material. The apparatus 10′ enables the interfacetemperature between the patient and the apparatus 10′ to be regulated.The cover 12 includes spaced inlet and outlet ports (not shown). Theinlet port is adapted to receive a conduit for blowing low-pressure airinto the cover 12. The outlet port may be vented to atmosphere or may beconnected to low-pressure vacuum source. The air blown into the cover 12flows through gaps formed between adjacent air cells 38 in the air cellgrid 36 and exits the cover 12 through the outlet port. FIG. 8schematically illustrates the flow of air through the gaps formedbetween adjacent air cells 38 of the air cell grid 36 with arrows. Thetemperature of the air being blown into the cover 12 may be controlledso as to control the interface temperature between the patient and theapparatus 10′.

From the above description of the invention, those skilled in the artwill perceive improvements, changes and modifications. For example, theair cell grid 36 may be regionalized so as to provide support forspecific portions of the patient's body. For example, the air cell grid36 may include a torso region, a lower limb region, etc. Suchimprovements, changes and modifications within the skill of the art areintended to be covered by the appended claims.

1-10. (canceled)
 11. An apparatus for supporting a patient during amedical procedure, the apparatus comprising: an air cell grid having aplurality of inflatable air cells, each air cell including a base walland an upper wall, the upper wall moving away from the base wall whenthe air cell is inflated into an expanded condition; and an electricalswitch for indicating a collapsed condition of an associated air cell ofthe air cell grid, the electrical switch including a first electricalcontact that is located on the base wall of the associated air cell anda second electrical contact that is located on the upper wall of theassociated air cell, the first and second electrical contacts cominginto engagement with one another in response to the associated air cellmoving into the collapsed condition.
 12. The apparatus of claim 11wherein the base wall and the upper wall of the associated air cell areformed from an electrically conductive material, the base wall formingthe first electrical contact and the upper wall forming the secondelectrical contact, a layer of insulating material being interposedbetween the base wall and the upper wall and including cutouts forenabling engagement of the first and second electrical contacts.
 13. Theapparatus of claim 11 wherein each air cell of the air cell gridincludes an electrical switch for indicating the collapsed condition ofthe air cell.
 14. The apparatus of claim 11 wherein the upper wall ofeach air cell, when the air cell is in the expanded condition, includessurfaces that are angled relative to the base wall to provide radiologictranslucency to the air cell grid.
 15. The apparatus of claim 14 whereinthe surfaces of the upper wall include a generally square base portionand a domed upper portion.
 16. The apparatus of claim 11 wherein the aircells of the air cell grid are divided into groups, each group includinga plurality of air cells that are interconnected with one another by airchannels.
 17. The apparatus of claim 16 wherein each group has anassociated valve, the valve being controllable for isolating the groupof air cells from other groups of the air cell grid and for placing thegroup of air cells in fluid communication with the other groups.
 18. Theapparatus of claim 11 further including a bead bag that is filled withcompressible beads and a layer of foam material that is located abovethe bead bag, the air cell grid forming an upper layer of the apparatusand providing a soft surface upon which the patient lies, the bead bag,when subjected to a vacuum, becoming rigid for supporting the air cellgrid against the patient for helping to maximize a surface area ofcontact between the patient and the apparatus.
 19. The apparatus ofclaim 18 further including a cover for surrounding the bead bag, thelayer of foam material, and the air cell grid, the cover being formedfrom a pliable elastic material.
 20. The apparatus of claim 19 whereinthe pliable elastic material of the cover is gas impenetrable, gapslocated between adjacent air cells of the air cell grid forming conduitsfor air flow through the apparatus for enabling control of an interfacetemperature between the patient and the apparatus.
 21. The apparatus ofclaim 18 wherein the layer of foam material provides a transitionbetween the soft surface of the air cell grid and a rigid surface of thebead bag, when the bead bag is subjected to vacuum, the transitionprovided by the layer of foam material helping to reduce shearexperienced by the patient.
 22. A method of supporting a patient on asupport structure having an air cell grid that includes a plurality ofinflatable air cells, the method comprising the steps of: inflating theair cells of the air cell grid into an expanded condition; venting theair cells of the air cell grid to atmosphere while maintaining the aircells in the expanded condition; isolating air cells of the air cellgrid from one another and from atmosphere; positioning the patient onthe support structure above the air cell grid; and placing the air cellsin fluid communication with one another to equalize air pressurethroughout the air cell grid for helping to equalize an interfacepressure between the patient and the support structure.
 23. The methodof claim 22 wherein the step of venting the air cells of the air cellgrid to atmosphere while maintaining the air cells in the expandedcondition further includes the step of equalizing air pressure withinthe air cells with atmospheric air pressure.
 24. The method of claim 22wherein the step of isolating air cells of the air cell grid from oneanother and from atmosphere includes closing valves associated with theair cells to prevent fluid communication with the isolated air cells.25. The method of claim 22 wherein the step of placing the air cells influid communication with one another to equalize air pressure throughoutthe air cell grid further includes preventing fluid communicationbetween the air cells of the air cell grid and atmosphere.
 26. Themethod of claim 22 further including the steps of: pulling a partialvacuum on a bead bag that is located beneath the air cell grid; moldingthe bead bag to provides support to the patient; and increasing thevacuum on the bead bag to rigidify the bead bag.
 27. The method of claim22 further including the step of monitoring the air cells to determinewhether an air cell has moved into a collapsed condition.